PERFORCE change 200153 for review

[John Baldwin]

http://p4web.freebsd.org/@@200153?ac=10

Change 200153 by jhb at jhb_jhbbsd on 2011/10/13 14:40:35

	Attempt to do fadvise() for writes.

Affected files ...

.. //depot/projects/fadvise/sys/kern/vfs_vnops.c#3 edit

Differences ...

==== //depot/projects/fadvise/sys/kern/vfs_vnops.c#3 (text+ko) ====

@@ -605,7 +605,8 @@
 	struct vnode *vp;
 	struct mount *mp;
 	int error, ioflag, lock_flags;
-	int vfslocked;
+	struct mtx *mtxp;
+	int advice, vfslocked;
 
 	KASSERT(uio->uio_td == td, ("uio_td %p is not td %p",
 	    uio->uio_td, td));
@@ -639,7 +640,32 @@
 	vn_lock(vp, lock_flags | LK_RETRY);
 	if ((flags & FOF_OFFSET) == 0)
 		uio->uio_offset = fp->f_offset;
-	ioflag |= sequential_heuristic(uio, fp);
+	advice = FADV_NORMAL;
+	if (fp->f_advice != FADV_NORMAL) {
+		mtxp = mtx_pool_find(mtxpool_sleep, fp);
+		mtx_lock(mtxp);
+		if (fp->f_advice != FADV_NORMAL &&
+		    uio->uio_offset >= fp->f_advstart &&
+		    uio->uio_offset + uio->uio_resid <= fp->f_advend)
+			advice = fp->f_advice;
+		mtx_unlock(mtxp);
+	}
+	switch (advice) {
+	case FADV_NORMAL:
+	case FADV_SEQUENTIAL:
+		ioflag |= sequential_heuristic(uio, fp);
+	case FADV_RANDOM:
+		/* XXX: Is this correct? */
+		break;
+	case FADV_NOREUSE:
+		/*
+		 * Request the underlying FS to discard the pages
+		 * after the I/O is complete.
+		 */
+		ioflag |= IO_DIRECT;
+		break;
+	}
+
 #ifdef MAC
 	error = mac_vnode_check_write(active_cred, fp->f_cred, vp);
 	if (error == 0)